Maximum Heat Production Research Articles

Green hydrogen energy source for a residential fuel cell micro-combined heat and power

In this paper, fuel cell micro combined heat and power with green hydrogen production is investigated for a residential house. Solar and wind energy were investigated for green hydrogen production. The performance of the micro-CHP system was evaluated using yearly energy coverage rate as an index, defined by the energy production and need ratio. A dynamic mathematical model of PEM fuel cell combined with the condensing boiler, supplied by local production of green hydrogen was developed. It was validated based on the yearly measurements in the FC micro-CHP unit installed in a French residential house. The key factors in the micro-CHP operating strategy were the fuel cell heat generation, stop phases, and regeneration which control water temperature, fuel cell life cycle, and annual performance. For conventional residential house in Normandy, the fuel cell operates for a short period during a summer day and the stored hot water was sufficient for heat demand. For winter typical day, the fuel cell operates continuously with maximum heat production. Electricity demand is satisfied and the condensing boiler is used to fulfill heat demand. Operating under heat led strategy, the yearly heat coverage rate is of 100% and the electricity coverage rate is usually upper 100% with 20 to 60% of stored electricity. Impact of the heating degree day and solar irradiance were analyzed using climatic zone factor as an index. Micro-CHP minimum hydrogen self-sufficiency of 57% is obtained in the coldest region where the climatic zone factor is 71°Cm2/W. Micro-CHP 100% hydrogen autonomy is achieved in regions where the climatic zone factor is lower than 39°Cm2/W.

Numerical Study on Heat Generation Characteristics of Charge and Discharge Cycle of the Lithium-Ion Battery

Lithium-ion batteries are the backbone of novel energy vehicles and ultimately contribute to a more sustainable and environmentally friendly transportation system. Taking a 5 Ah ternary lithium-ion battery as an example, a two-dimensional axisymmetric electrochemical–thermal coupling model is developed via COMSOL Multiphysics 6.0 in this study and then is validated with the experimental data. The proportion of different types of heat generation in a 26,650 ternary lithium-ion battery during the charge/discharge cycle is investigated numerically. Moreover, the impact of essential factors such as charge/discharge multiplier and ambient temperature on the reaction heat, ohmic heat, and polarization heat are analyzed separately. The numerical results indicate that the total heat generated by the constant discharge process is the highest in the charging and discharging cycle of a single battery. The maximum heat production per unit volume is 67,446.99 W/m3 at 2 C multiplier discharge. Furthermore, the polarization heat presents the highest percentage in the charge/discharge cycle, reaching up to 58.18% at 0 C and 1 C multiplier discharge. In a high-rate discharge, the proportion of the reaction heat decreases from 34.31% to 12.39% as the discharge rate increases from 0.5 C to 2 C. As the discharge rate rises and the ambient temperature falls, the maximum temperature increase of the single-cell battery also rises, with a more pronounced impact compared to increasing the discharge rate.

Prediction and optimization of productivity and lifespan in multi-well enhanced geothermal system

Engineering case studies have revealed that multi-well enhanced geothermal system is efficient for large-scale geothermal energy utilization. However, current research on the productivity and lifespan of multi-well enhanced geothermal system is limited to rough estimation by thermal storage volume, without a fast and accurate prediction method. To solve this problem, the multi-well enhanced geothermal system is divided into several double-well enhanced geothermal systems. The numerical simulation and previous empirical formulas for double-well enhanced geothermal system are used to propose a new multi-well enhanced geothermal system empirical formula in this study. The proposed formula is applicated using the Rehai geothermal field in Yunnan, China by three-well model and six-well model respectively. The results show that the heat production and lifespan of the enhanced geothermal system with six wells arrangement are higher compared to the three wells arrangement. Moreover, the productivity and lifespan of enhanced geothermal system with injection pressure difference and injection temperature of 1.0 MPa and 293.16 K for thermal medium are significantly better than those of 2.5 MPa and 353.16 K, respectively. Therefore, during enhanced geothermal system construction, both productivity and investment should be considered, and the number of injection wells should be maximized. Low-temperature thermal medium and low injection-production pressure differences should be selected for maximum heat production during the operation. This research presents a fast and accurate prediction method for predicting and evaluating the heat transfer performance of large-scale multi-well EGS which is helpful for EGS commercial use.

The Effect of Heat Treatment on Wear Properties of Ni-B-CNT Electroless Coating with Different Carbon Nanotube Concentration on AISI 4340 Steel

Study wear resistance for heat treatment of Ni-B-CNT electroless coatings. Different concentrations for CNT (0 ,0.35 and 0.7 g/l Ni-B-CNT composite coatings deposition on 4340 steel. After the procedure of coating, all samples were heat treatment. The test wear of a coating was valued with pin on disk technique. Preparation of Ni–B–CNT electroless coatings are with using nickel chloride in alkaline bath, borohydride and Multi walled carbon nanotubes. characterization with FESEM, micro hardness, XRD and surface roughness. Study for surfaces of worn with EDS and FESEM. Micro hardness results are show that the larger hardness1010 HV is gained by heat treatment for coating (Ni-B- 0.35 g/L CNT) because of concentration CNT caused structure conversion for coating Ni-B from amorphous to crystalline. Also, CNT prevent maximum heat production and decrease of the friction coefficient during test wear. CNT aggregation was noted result the presence for more particles (Ni-B - 0.7g/l CNT) that occur create roughness and also lead to increase in rate of wear because of big particles with weakly joined in matrix of Ni.

Radiogenic heat production estimation towards sustainable energy drive in northeastern Nigeria

An estimate of the radiogenic heat production (RHP) across the different petrologic units of northeastern, Nigeria was previously not performed. Hence, their geothermal potentials are not widely known. However, an airborne radiometric data of equivalent uranium, (eU), equivalent thorium (eTh,) and percentage potassium (% K) acquired by Nigerian geological survey agency (NGSA) in the year 2009 was deployed in the evaluation of the RHP across the major petrologic outcrops of northeastern, Nigeria. The objective of this study is to estimate the quantity of RHP across the 13 petrologic units of the northeastern Nigerian terrain via the use of an empirical equation (RHP=ρ(0.0952Cu+0.0256CTh+0.0348Ck)). The petrologic units studied are; medium-coarse grained biotite-hornblende granites (OGe), porphyritic biotite-hornblende granites (OGp), banded gneiss (bG), charnokytes (Ch), ignimbrites (JYG), migmatites-gneiss (MG), basalts (bb), Gombe sandstones (GS), Pindiga Formation (PS), Yolde Formation (YL), Bima sandstones (BS), Keri-Keri Formation (KK), and alluvium (AL). Basic/preliminary processing such as; signal integration, signal validation, and examination of spurious data were applied prior to the RHP computation. The results of the heat production analysis performed show the range of RHP to be from 1.11μW/m3 to 3.35μW/m3 Hence, the maximum heat production value of 3.35μW/m3 was recorded along porphyritic biotite-hornblende granites (OGp) rock block, while the least value of 1.11μW/m3 was recorded over alluvium (AL) rock outcrops. Furthermore, the spatial distribution of the RHP values over the study location shows a gradual increase from the middle, low heat production (sedimentary zones) to the high heat producing areas (granitic and metamorphic zones) around eastern and western parts. The petrologic units arranged in order of decreasing magnitude of radiogenic heat generation are; OGp > MG > OGe/bG > bb > GS > Ch > JYG > BS > PS/YL > KK > AL. On a general note, the petrologic units studied were classified as low in terms of geothermal character based on comparison with other previous global RHP studies.

Investigation into the effects of emergency spray on thermal runaway propagation within lithium-ion batteries

Inhibition a battery's thermal runaway propagation can avoid serious accidents in electric vehicles. Emergency spray has been proven to be effective in suppressing thermal runaway of a single cell, but the effect of inhibiting thermal runaway propagation between multiple batteries still needs further investigation. In this study, the characteristics of thermal runaway propagation was experimentally investigated, and the emergency spray technology, with different cooling durations, was applied in various stages of thermal runaway propagation. The results indicated that the continuous spray could not only reduce the average maximum temperature, but also delay the diffusion among multiple batteries and provide further response time. However, after-combustion was a frequent occurrence when the spray shut down. A correlation model was proposed to evaluate the maximum heat production of lithium-ion batteries by calculating the enthalpy and mass of the reactants and short circuit energy. The required cooling quantity is determined by experiment and verified by experiment. These results could help the development of a cooling strategy for suppressing the thermal runaway propagation effectively with minimum cooling capacity.

Thermal power extraction from a deep, closed-loop, multi-level, multi-branch, U-shaped borehole heat exchanger geothermal system

A novel closed-loop, multi-level, multi-branch, U-shaped borehole heat exchanger geothermal system is proposed to achieve a more efficient method to exploit deep geothermal resources. Compared with single U-shaped closed-loop geothermal systems, the new system can reduce the drilling cost and increase the heating length. In this study, first, a three-dimensional unsteady-state flow and heat transfer model was established. Then, the temperature distribution of the working fluid in the tube and a hot dry rock reservoir was analyzed. Third, the key factors that influence heat production were analyzed. The results show that increasing the injection rate blindly does not improve the heat production power; the maximum heat production power can only be obtained by controlling the injection rate to a certain extent. The heat production power has a good linear relationship with reservoir temperature and horizontal well length. Under different reservoir temperatures, the unit power generation price of the proposed geothermal system reaches the lowest value when the horizontal well length is 3000 m and the horizontal well branches number is 4. Overall, this novel design can improve the heat exchange efficiency, reduce the power generation cost and can serve as a reference for the study of exploiting deep geothermal resources.

High-altitude deer mice depend on blood fuel supply for warmth

They may not look like it, but high-altitude deer mice are metaphorically on fire. With an astronomically fast metabolism evolved to combat the twin challenges of living at high altitude –maintaining their warm body temperature while living in chilly thin air – the tiny mammals are well prepared for their mountain existence. To stoke their heating, the deer mice fuel their internal inferno with fat: ‘Highland deer mice burn fats faster for maximum heat production than when they are exercising’, says Sulayman Lyons from McMaster University, Canada. But it wasn't clear exactly how they managed to mobilise enough fatty fuel to meet their extraordinary heat production demands. So, Lyons and Grant McClelland (McMaster University) collected deer mice from the summit of Mount Evans, CO, USA (4350 m) and low altitude Nine-mile Prairie, NE, USA (320 m), to find out how the animals manage their fuel supplies in warm low altitude conditions and in a chilly mountain top simulation.‘We simulate high altitude conditions by keeping mice in special chambers, which lower the air pressure, in a cold room’, says Lyons, who kept deer mice originating from both the mountain and prairie at 5°C in the air pressure experienced at ∼4300 m for 6 weeks, while other deer mice basked in warm (∼23°C) lab air. He then measured the metabolic rates of some of the animals at the temperature and air pressure at which they had been living in the lab, while also measuring the metabolic rates of the animals as he chilled them to extreme mountain temperatures (–10°C) in thin air. Then he collected blood samples, fat and muscle from all of the deer mice, to find out how they managed and mobilised their fat reserves.Comparing the deer mice that originated from the lowland prairies with the highland deer mice as they adjusted to life on the simulated mountain top, both groups of animals increased the amount of fat they released from their white fat stores into their blood to fuel their higher metabolisms in the thin cold air. In addition, the deer mice that had originally lived at high altitude in Colorado carried more triglyceride fats in their blood, which could be used as fuel by their muscles and brown fat to produce warmth.Lyons also measured the quantities of two different types of fat (non-esterified fatty acids and triglycerides) in the blood of resting deer mice and when the animals had to work harder because they were breathing high-altitude thin cold air. The deer mice that had been born at high altitude were able to boost the amount of fat in their blood enormously, increasing the non-esterified fatty acids 3.1-fold and triglycerides by a massive 7.1-fold, when their bodies needed the fuel to keep warm in the chilly mountain conditions.However, when he checked for evidence of the proteins that are responsible for transporting fuel fats into the muscle cells and brown fat that generate heat, the low- and high-altitude deer mice had essentially the same quantities of fat-transporting proteins within the tissues. The differences in the animals’ metabolisms were entirely down to their abilities to transport fats in their blood, with deer mice that make their homes amongst the mountain peaks supplying more fuel through the blood to their muscle and brown fat furnaces.Lyons also suspects that the mini mountaineers devote more muscle to shivering than they use when moving, which could account for the deer mouse's extraordinarily high rates of fuel consumption when keeping warm at altitude.

Synergetic mining of geothermal energy in deep mines: An innovative method for heat hazard control

The ongoing depletion of shallow resources has led to the mining of progressively deeper deposits, where high-temperature thermal stresses pose heat hazards and threaten worker safety. Mitigating geothermal hazards is therefore an essential component of mining operations in deep mines. In this paper, a novel synergetic mining approach is proposed that controls heat hazards at low cost and simultaneously exploits mineral and geothermal energy. Injection and production channels are designed below the ventilation tunnel to synchronously cool the tunnel surrounding rock and exploit mine geothermal energy. A fully coupled numerical model is established that simultaneously simulates heat and mass transfer in a large-scale ventilation network and geological reservoir. The cooling effect on the tunnel and heat recovery capacity of geothermal exploitation are investigated to assess the feasibility of the proposed scheme. Three case studies are presented to identify the impact of the water injection and production channel layout on the heat and mass transfer characteristics in the rock layer. The temperature of the tunnel surrounding rock is cooled over a few years via low-temperature water injection into the mine and heat production in the deep rock layer; this rapidly reduces the air temperature inside the tunnel. The total heat production rate initially rapidly increases and then gradually decreases. In the ninth year, the maximum heat production rate of the production channel reached 6.01 × 103 kW. The cooling effect on the roadway and heat production performance are optimal when the water injection channel is arranged under the air intake side of the main ventilation roadway of the mine and the heat production channel is arranged in the deep rock under the return air side of the roadway. After 4 years of water injection, the temperature at the end of the tunnel in Case 1 rapidly decreased to 30.9 °C; this temperature is 6.6 °C and 3.4 °C lower than those in Cases 2 and 3, respectively. Longer injection channel lengths can significantly reduce the injection pressure requirement in the injection channel. Shorter distances between the injection channel and tunnel are associated with faster reductions of the tunnel temperature. This technique significantly improves the thermal comfort inside the tunnel and produces considerable geothermal energy; a single heat production channel can produce 1.68 × 1015 J over a period of 10 years.

Multi-objective optimization of a clean combined system based gasifier-solid oxide fuel cell

Biomass can be used as fuel of fuel cells by conducting thermochemical process such as biomass gasification. In this study, the required fuel of a solid oxide fuel cell was supplied through pine gasification in a gasifier reactor. The purpose of this study was provided an appropriate configuration to a co-generation system produced heat and power and the state with maximum heat and power production and minimum carbon dioxide emission was obtained. The outputs were power, heat, and CO2 emission investigated with respect to steam to biomass ratio of gasification and current density and fuel utilization factor of solid oxide fuel cell. The results indicated that fuel utilization factor contributed the most on power and hot water with shares of 73.64% and 47.27%, respectively. However, current density had the highest influence on carbon dioxide emission with a share of 83.41%. Parametric analysis illustrated that increasing fuel utilization factor remarkably enhanced the power production and mitigated hot water production. A considerable reduction was observed in carbon dioxide emission by increasing current density. Single-objective and multi-objective optimizations revealed that steam to biomass ratio of 2, 4600 A/m2 of current density, 0.77 of utilization factor are the optimum states. Power production of 196.8 kW, hot water production of 1203 g/s, and carbon dioxide emission of 1261 kg/MW.h were the outputs of the optimum state.

The Assessment of the Maximum Heat Production and Cooling Effectiveness of Three Different Drill Types (Conical vs. Cylindrical vs. Horizontal) during Implant Bed Preparation—An In Vitro Study

The aim of this experimental study was to verify thermal diffusion differences, by measuring the maximum temperature achieved with different drill shapes. Synthetic bone blocks of type I density made from solid rigid polyurethane (PUR) foam were used to perform the drilling procedures. The experiment was conducted at three different rotation speeds: 800, 3000 and 5000 rpm. Conical drills (with and without an internal cooling hole) were compared with horizontal drills and disc drills. The temperature during drilling for implant bed preparation was estimated with the use of thermocouples and an infrared (IR) camera. The temperature during drilling with disc cutters for lateral basal implants did not exceed 33 ∘C and the temperature decreased in proportion to higher drill speed. The results indicate that the tested design is safe and will not cause bone overheating.

The effect of the particle size on the heating and drug release potential of the magnetic nanoparticles in a novel point of view

The present study is written to provide an overview of the effect of the particle size on the heating and drug release potential of the magnetic materials under magnetic fields. As a symbol representing the change of particle size, a dimensionless σ parameter is defined by dividing anisotropic energy by the thermal one. According to the obtained results, at the boundary of ferromagnetic and superparamagnetic nanoparticles (σ≈1), there is the maximum heat production. On the other hand, single-domain nanoparticles with the largest size (σ≫1) have the lowest releasing heat under AC magnetic field. There is also a considerable heat production under AC magnetic fields for both superparamagnetic (σ < 1) and soft-ferromagnetic materials (σ > 1). However, the results are significantly different when MNPs are used as heating cores in drug release systems. Here, the soft-ferromagnetic materials have a low heating and hence low drug release potential. According to the results obtained, increasing σ causes three important events. The first is the reduction of the spin canting effect which results in the amplification of the spin rotations in the same direction and hence a higher potential of Neel heating mechanism. The second is the growth of the macrospin size which leads to more spin torque and hence more heating energy. The third is blocking the macrospin and consequently activation of the Brownian heating mechanism. However, the results are significantly different when MNPs are used as heating cores in drug release systems. Here, the soft-ferromagnetic materials have a low heating and hence low drug release potential. As a reason one can say that in drug release systems, there are barriers to activation of the Brownian mechanism which reduce the heating and drug release potential of soft-ferromagnetic nanoparticles.

Composition and metabolism of fecal microbiota from normal and overweight children are differentially affected by melibiose, raffinose and raffinose-derived fructans

The aim of the study was to investigate the metabolism of non-digestible oligo- and polysaccharides by fecal microbiota, using isothermal microcalorimetry. The five tested substrates were raffinose, melibiose, a mixture of oligo- and polysaccharides produced from raffinose by levansucrase, levan synthesized from raffinose, and levan from timothy grass. Two inocula were comprised of pooled fecal samples from overweight or normal-weight children, from healthy adult volunteers and a pure culture of Bacteroides thetaiotaomicron as a reference bacterium for colon microbiota. The growth was analyzed based on the heat evolution curves, and the production of organic acids and gases. Taxonomic profiles of the microbiota were assessed by 16S rDNA sequencing.Raffinose and melibiose promoted the growth of bifidobacteria in all fecal pools. Several pool-specific substrate-related responses to raffinose and melibiose were revealed. Lactate-producing bacteria (Streptococcus and Enterococcus) became enriched in the pool of overweight children resulting in lactic acid as the major fermentation product on short saccharides. Acetic and butyric acids were prevalent at fermentation in the normal-weight pool coinciding with the enrichment of Catenibacterium. In the adult pool, the specific promotion of Bacteroides and Lachnospiraceae by levans was disclosed. In the fecal pool of normal-weight children, levans stimulated the growth of Senegalimassilia and Lachnoclostridium and this particular pool also showed the highest maximum heat production rate at levan fermentation. Levans and raffinose-derived oligosaccharides, but not raffinose and melibiose were completely fermented by a pure culture of Bacteroides thetaiotaomicron.The main conclusion from the study is that fecal microbiota of normal and overweight children have different compositions and they respond in specific manners to non-digestible oligo- and polysaccharides: raffinose, melibiose, raffinose-derived oligosaccharides and levans. The potential of the tested saccharides to support a healthy balance of colon microbiota requires further studies.

Microcalorimetry combined with chemometics for antibacterial evaluation of Sophora alopecuroides on Staphylococcus aureus

This study aimed to evaluate the antibacterial activities of Sophora alopecuroides from various production regions of China on Staphylococcus aureus by microcalorimetry and chemometics. From the heat-flow power–time curves of S. aureus growth affected by the extracts of S. alopecuroides, some vital thermokinetic parameters, such as the growth rate constant (k), the maximum heat-production rate (Pm), the appearance time (tm) and the total heat-production (Q), were obtained and were analyzed by principal component analysis and hierarchical cluster analysis. The results showed that all the S. alopecuroides samples expressed strong antibacterial activities to S. aureus, but the activities varied evidently on their production regions. The samples from Xinjiang (northwest region of China) showed the strongest antibacterial activities with inhibitory ratio (I) of 81.3%, while those from Inner Mongolia (North region of China) gave the contrast results with I of 9.2%. The findings indicated that the anti-S. aureus activities of S. alopecuroides had close relationship with the production regions. This study has provided a combined model of microcalorimetry and chemometrics to evaluate the antibacterial activities of medicinal herbs on bacteria.

Experimental investigation of the daily performance of an integrated linear Fresnel reflector system

The objective of this work is to investigate the daily and the instantaneous performance of a linear Fresnel reflector (LFR) experimentally and numerically. The examined LFR has an inverted flat plate receiver with a 36 m2 total collecting aperture area and is coupled to a storage tank of 1 m3 volume. This system is investigated experimentally for daily operation in the period from May to October for the climate conditions of Athens (Greece), using water as the working fluid (temperature levels up to 100 °C). Moreover, a detailed mathematical model for the prediction of the instantaneous and of the daily performance is developed. This model is validated with the experimental results for 52 operating days and it estimates the daily useful energy production with a mean error of 3%. This modeling is based on the energy balance on the collector loop and the storage tank. The emphasis is given on the determination of the optical losses of the collector, which are associated with the sun position during the day. It is found that the maximum useful heat production is about 8.4 kW, while the maximum daily heat production is about 260 MJ. The results of this work can be exploited for the evaluation of integrated solar concentrating systems and especially of linear Fresnel reflectors.

Design of one axis three position solar tracking system for paraboloidal dish solar collector

Solar Tracking System plays a vital role in the maximum generation of solar energy. However, the design of the sun tracker which was currently in use is very complicated and expensive. Those sun tracker units are heavy and seems to be difficult to install and prone to breakdown. This project aims to design an automatic Solar Tracking system which overcomes the above mentioned problems. In this process one axis three position solar tracking system was developed, to reduce the complexity and to shut down the cost and the same has been tested. Taking into consideration, the high efficiency with the lower cost, Light Dependent Resistor (LDR) sensors have been used in this project to track the sunlight position. Two LDR sensors one facing East and other facing West senses the intensity of sunlight and the result will be compared. The difference in the intensity will be calculated by the Programmable Interface Controller (PIC controller) which was fixed below the paraboloidal dish solar collector. If there is any difference in values, the controller sent the signal to the DC geared motor that passes through the amplifier which amplifies the signal according to that of DC geared motor. At once the motor receives the signal it tilts the solar collector. The above process will continue till the intensity of sunlight received by both the sensors is same. In this way, paraboloidal dish solar collector collects the maximum sunlight which will be converging to a black receiver for the maximum heat production. The test result shows that, the one axis three position tracking device is able to track and follow the Sunlight intensity in order to get maximum solar energy in the form of heat irrespective of the motor speed.

Microbial, Urease Activities and Organic Matter Responses to Nitrogen Rate in Cultivated Soil

Nitrogen (N) fertilizer is an important field management, this paper was to investigate the responses of microbial activity measured by microcalorimetric technique, urease activity and organic matter to proper nitrogen (N) fertilizer in cultivated system in the North China Plain. The microcalorimetry results showed that microorganisms under proper N fertilizer rate got the efficient metabolism. The maximum heat production (Pmax) of microcalorimetry parameter implied that increasing the N fertilizer rate, Pmax did not increase always but firstly increased than decreased. In addition, from soil urease activity and organic matter studies, high soil urease activity due to both N fertilizer rate and growth stage and these had light influence on soil organic matter. These results suggest that only proper amount of N fertilizer rate and suitable topdressing for a good wheat-growing environment.

Solar Radiation during Rewarming from Torpor in Elephant Shrews: Supplementation or Substitution of Endogenous Heat Production?

Many small mammals bask in the sun during rewarming from heterothermy, but the implications of this behaviour for their energy balance remain little understood. Specifically, it remains unclear whether solar radiation supplements endogenous metabolic thermogenesis (i.e., rewarming occurs through the additive effects of internally-produced and external heat), or whether solar radiation reduces the energy required to rewarm by substituting (i.e, replacing) metabolic heat production. To address this question, we examined patterns of torpor and rewarming rates in eastern rock elephant shrews (Elephantulus myurus) housed in outdoor cages with access to either natural levels of solar radiation or levels that were experimentally reduced by means of shade cloth. We also tested whether acclimation to solar radiation availability was manifested via phenotypic flexibility in basal metabolic rate (BMR), non-shivering thermogenesis (NST) capacity and/or summit metabolism (Msum). Rewarming rates varied significantly among treatments, with elephant shrews experiencing natural solar radiation levels rewarming faster than conspecifics experiencing solar radiation levels equivalent to approximately 20% or 40% of natural levels. BMR differed significantly between individuals experiencing natural levels of solar radiation and conspecifics experiencing approximately 20% of natural levels, but no between-treatment difference was evident for NST capacity or Msum. The positive relationship between solar radiation availability and rewarming rate, together with the absence of acclimation in maximum non-shivering and total heat production capacities, suggests that under the conditions of this study solar radiation supplemented rather than substituted metabolic thermogenesis as a source of heat during rewarming from heterothermy.

Reduced Chemical Kinetic Model of Toluene Reference Fuels for HCCI Combustion

We developed a reduced kinetic model for toluene reference fuel (TRF) including 70 species and 196 reactions for homogeneous charge compression ignition (HCCI) combustion. The low temperature reaction scheme for the TRF was based on the existing low-temperature reaction mechanism developed by Tanaka for primary reference fuel (PRF) oxidation. We added skeletal reactions for PRF oxidation to a reduced toluene sub-mechanism. The high-temperature reaction mechanism was mainly from the previous work of Patel and an important TRF reaction [H+O2+M=O+OH+M] was added. Validation of the ignition delay time was performed for single-component, two-component and three-component fuels and the results were satisfactory for HCCI engine conditions. A comparison of various experimental data available in the literature, including shock tube tests and HCCI engine experiments, shows that the present TRF mechanism performs well. A sensitivity analysis at the moment of maximum heat production shows that the reaction of phenol radicals (C6H5) with O2 is more sensitive as the pressure increases. Formaldehyde (HCHO) is a very important intermediate species and should not be neglected.

Can a herb and white clover mix improve the performance of multiple-bearing ewes and their lambs to weaning?

The productive performance of highly fecund ewes and their progeny on ryegrass-based swards is limited in late pregnancy and lactation. Alternative herbages, such as chicory, plantain and red and white clover, have the potential to improve performance levels. In the present study, 49 twin- and 42 triplet-bearing Romney composite ewes bred to either Suffolk or Romney rams were allocated to one of three nutritional treatments from Day 131 of pregnancy [19 twin ewes on a ryegrass–white clover sward mix (Rye/WC); 16 twin ewes on a plantain–ryegrass sward mix (Plant/Rye); 14 twin ewes on a chicory–plantain–red and white clover sward mix (Herb); 13 triplet ewes on Rye/WC; 16 triplet ewes on Plant/Rye; and 13 triplet ewes on Herb] and remained on these sward treatments with their lambs until 75 days after the midpoint of the lambing period (L75). Nutritional treatment had no effect (P &gt; 0.05) on ewe liveweight, body condition score (BCS) or non-esterified fatty acid and β-hydroxybutyrate concentrations on Day 145 of pregnancy. At L75, ewes on the Herb treatment sward were heavier than ewes on Plant/Rye (70.75 ± 1.31 v. 61.43 ± 1.28 kg, respectively) and had a higher BCS than ewes on either Plant/Rye or Rye/WC (2.7 ± 0.1, 2.2 ± 0.1 and 2.3 ± 0.1, respectively). Sire type and nutritional treatment had no affect (P &gt; 0.05) on lamb birthweight or weight at L75. At L20, lambs born to ewes on the Herb sward treatment were heavier than those on the Rye/WC and Plant/Rye treatments (8.74 ± 0.23 v. 7.98 ± 0.23 and 7.79 ± 0.22 kg, respectively; P &lt; 0.05). Neither birth rank, sire type nor ewe treatment had any effect (P &gt; 0.05) on maximum heat production on a per kg liveweight basis or total heat production. Romney-sired lambs on the Herb sward treatment had higher (P &lt; 0.05) survival rates than those on the Rye/WC sward treatment (97.8% v. 61.7%, respectively). However, no such relationship was observed in lambs born to Suffolk sires (79.8% v. 84.8%, respectively). The survival response resulted in greater (P &lt; 0.05) total liveweight of Romney-sired lambs at L75 per ewe on the Herb nutritional treatment than on the Rye/WC treatment (61.6 ± 5.0 v. 36.7 ± 4.6 kg, respectively) a relationship not observed (P &gt; 0.05) in Suffolk-sired lambs. In conclusion, the present study indicates that there is the potential to improve the productive performance of multiple-bearing ewes and their lambs by grazing on a Herb sward mix.